Prior to the instant invention, tube blankets, which may be in the shape of U tubes, are formed with vent holes that have the same dimension. Accordingly, the warm air that outputs from the portions of the U tube blanket that are remote from the air input source tends to be colder than the warm air that outputs from the portions of the blanket close to where the heated air from a convective warmer is input. Thus, uneven warming of the patient results.
There is therefore a need for a U-shaped type convective warming blanket that can bathe a patient with an evenly distributed envelope of warm air.